The invention relates to a constant current switch for controlling a largely constant switchable load current in the case of a fluctuating supply voltage.
For example a constant and relatively high current is required to modulate high-output infra-red diodes. Thus it is required that a constant transmission power of the infra-red diodes should be guaranteed over as large as possible a voltage range even with a fluctuating and falling supply voltage, these infra-red diodes being used in many cases for data transmission paths.